Ultrasonic testing system and method

ABSTRACT

A comprehensive system for the cleaning, inspection, and testing of tubulars, particularly riser pipes, is provided. In a first aspect, a method of inspecting a tubular comprises cleaning, visually inspecting, corrosion mapping, and TOM testing the tubular. In another aspect, a specially designed or adapted tool is provided for each of the steps of the method.

This is a Division of U.S. patent application Ser. No. 09/727,130 filedNov. 29, 2000, now U.S. Pat. No. 6,684,706.

FIELD OF THE INVENTION

The present invention relates generally to the field of non-destructivetesting and, more particularly, to a method and apparatus for cleaningand inspecting tubulars, including inspecting for flaws in pipesequentially using pulse echo and time of flight diffraction (TOFD).

BACKGROUND OF THE INVENTION

There has long been a need for methods of cleaning and inspectingtubulars, particularly offshore riser pipe, on site. Typical methodsused today include disassembling the riser pipe from a rig, transportingthe riser pipe to a yard, and there conducting inspection and testing ofthe tubular using well known techniques. Such a method is not onlyexpensive and time consuming, but also very disruptive of normaloperations on the rig.

Thus, there remain a need for a system and method of inspecting tubularson site to minimize down time of the rig, and to save the costs oftransporting and returning the tubulars under inspection.

Even the techniques used at the yard for the testing and inspection oftubulars have certain drawbacks. Various techniques have been developedto detect flaws in structures, particularly welds in such structures.The ability to detect flaws in structures such as tubulars in drillingand production rigs and pipelines is especially critical before anycatastrophic failure occurs.

Ultrasonic testing of metal structures has proved to an effective andpractical tool for nondestructive testing (NDT). Known ultrasonictechniques typically yield reliable examination results. However, somegeometries make known ultrasonic techniques difficult or even impossibleto apply, or yield inaccurate results.

One technique that has gained common acceptance in the NDT field isreferred to as the echodynamic technique. This technique consists ofmeasuring the duration of the defect echo in axial or circumferentialtube direction when the ultrasonic probe (in pulse-echo mode) is movedover the defect. Such a defect may involve slag, porosity, stresscracking, or other anomalies from the anticipated metal grain structure.In the pulse-echo mode, the depth of a defect is calculated from theprobe displacement distance at which a defect echo was picked up. Todetect the defect, the amplitude of the defect echo should be abovenoise level. However, many defects that are of particular concern escapedetection if they are oriented in a particular way relative to theapplied pulse echo, because this technique relies on the reflectivity ofthe defect. In fact, the pulse echo technique is used in the presentinvention for corrosion mapping in determining pipe wall thickness.However, as previously described, the pulse echo technique may misscertain flaws, and this fact has lead to the development of othertesting techniques.

The Time of Flight Diffraction technique (TOFD) was developed by theAEA's Harwell Laboratory in Britain in the mid seventies as a method ofaccurately sizing and monitoring the through-wall height of in-serviceflaws in the nuclear industry. For weld inspection, it was quicklyrecognized that the method was equally effective for the detection offlaws, irrespective of type or orientation of the flaw, since TOFD doesnot rely on the reflectivity of the flaw. Rather, TOM detects thediffracted sound initiating from the tips of the flaw.

In TOFD, a transmitting probe emits a short burst of sound energy into amaterial and the sound energy spreads out and propagates in an angularbeam. Some of the energy is reflected from the flaw but some of theenergy is incident to the flaw and is diffracted away from the flaw. Afraction of this diffracted sound travels toward a receiving probe. Thediffracted signals which are received by the receiving probe are timeresolved using simple geometry calculations and are graphicallydisplayed in a grey scale form.

While the TOFD technique has proved effective for many geometries, thereremains a need for a method and system for detection of flaws fromwithin a cylindrical structure, such as a pipe or riser stanchion. Thepresent invention is believed to be the first structure and method ofNDT using TOFD from within a tubular such as a riser pipe.

SUMMARY OF THE INVENTION

The present invention addresses these and other needs in thenon-destructive testing art by providing a comprehensive system for thecleaning, inspection, and testing of tubulars, particularly riser pipes.In a first aspect of the present invention, a method of inspecting atubular comprises cleaning, visually inspecting, corrosion mapping, andTOFD testing the tubular. The present invention is also adapted for usewith new construction in which the cleaning step may not be necessary insome cases. In another aspect of the invention, a specially designed oradapted tool is provided for each of the steps of the method.

The step of cleaning the inside of the tubular includes pre-wetting, ifdesired, to remove loose debris and to soften dried drilling fluids andother materials. An air motor driven wire brush with an alignment toolis then pulled or pushed through the tubular. For small lines, which mayinclude weld material protruding into the cylindrical space, a cuttingtool is also provided to precede the wire brush. The wire brush may alsobe followed by a jet spray of water to wash away cuttings, rust, anddust.

The step of visual inspection comprises moving a camera throughout thetubular. A digital linear placement transducer, referred to as anencoder, is provided to precisely locate the camera within the tubular.The camera provides a video signal to a computer and to a recorder for apermanent record.

The step of corrosion mapping employs a pulse echo system to map wallthickness of the tubular. A drive system is provided to move the toolholding the pulse echo probes through the tubular, and the computer onceagain makes a record of the mapping. Finally, a TOM system is providedto detect flaws in the tubular seam and girth welds, such as inservicedefects, stress and fatigue cracking, corrosion, erosion, weldfabrication defects, lack of fusion (LOF), slag porosity, and otherdefects.

These and other features of the invention will be apparent to thoseskilled in the art from a review of the following description along withthe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a is a side view in partial section of a cleaning system inaccordance with this invention for cleaning a large ID pipe, such as a21″ ID main riser pipe.

FIG. 1 b is an end view of the cleaning system of FIG. 1 a.

FIG. 2 is a side view in partial section of a cleaning system forcleaning smaller ID pipe, such as 3″ and 4″ pipes.

FIG. 3 a is a side view in partial section of a system for the visualinspection of the larger diameter pipe.

FIG. 3 b is an end view of the visual inspection system of FIG. 3 a.

FIG. 4 a is a side view in partial section of a system for the visualinspection of small ID pipe, such as for a 3″ or 4″ nominal ID pipe.

FIG. 4 b is an end view of the visual inspection system of FIG. 4 a.

FIG. 5 a is a side view in partial section of a system for performingcorrosion mapping inspection of a large diameter pipe.

FIG. 5 b is an end view of the system of FIG. 5 a.

FIG. 5 c is a side section view of corrosion mapping tool suitable foruse in the inspection system of FIGS. 5 a and 5 b.

FIG. 6 a is a side view in partial section of a system for performingcorrosion mapping inspection of a small diameter tubular.

FIG. 6 b is an end view of the system of FIG. 6 a.

FIGS. 6 c and 6 d are side section views of corrosion mapping tools for3″ and 4″ nominal ID tubulars, respectively, suitable for use in thesystem of FIGS. 6 a and 6 b.

FIG. 7 is a side view in partial section of a preferred system forperforming TOFD testing of a large diameter pipe.

FIG. 8 a is a side view in partial section of a preferred system forperforming TOFD testing of a small diameter tubular.

FIGS. 8 b and 8 c are side section views of TOFD tools for performingtesting of 4″ and 3″ tubulars, respectively, suitable for use with thesystem of FIG. 8 a.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention includes a system for the inspection of tubularsand a method of conducting such an inspection using the system. Thesystem of the invention includes the systems for carrying out thevarious stages of inspection, as well as the tools which have beendesigned or specially adapted for the inspection. The method of theinvention comprises primarily four steps: (1) cleaning; (2) visualinspection; (3) corrosion mapping; and (4) TOFD inspection. Thefollowing description follows through the four steps of the method, withthe structure described during each step.

Cleaning

FIGS. 1 and 1 a show the arrangement for cleaning the main, 21″ ID riserpipe 10. At one end of the pipe 10 is coupled a winch assembly 12 drivenby a winch motor 14 and the winch assembly 12 is adapted for mounting toa flange 16 of the pipe 10. A wire line 18 is wound on a winch spool 20,enough wire line to reach the entire length of the pipe 10. The end ofthe wire line 18 terminates in a swivel 22, which couples to a cleaningtool 24. As used herein, the term “drawing system” refers to themechanism for drawing the cleaning tool through the pipe, and includesthe winch assembly 12, the winch motor 14, and the wire line 18.

On the opposite end of the pipe 10 is mounted a drive mechanism 26 toactuate the cleaning tool 24. The drive mechanism 26 includes a motormount 28 on which is mounted an air motor 30. The motor mount 28 alsoincludes at least two guide bars 32 which slidingly extend intoauxiliary lines 34 and the guide bars are preferably about 3.5 feetlong. The air motor 30 is provided with an air supply 36, which may beany available air supply of about 120 psi. Coupled to the drive shaft ofthe air motor is a drive tube 38, which is preferably made up of 3′sections, and the sections of drive tube 38 may be quickly and easilymade up with couplings 40. The end of the drive arm or tube 38 oppositethe drive motor 30 is coupled to the cleaning tool 24. The cleaning tool24 includes a pair of wire brushes 42 and 44, separated by a centralizerring 46, which maintains the cleaning tool in alignment within the pipe10 to ensure complete circumferential cleaning of the inside of thepipe. Finally, speed control for the air motor 30 is provided by an airregulator and dryer 48 for complete control of the cleaning operation.

To begin the procedure of cleaning the inside of the main pipe 10, theinside of the pipe is first flushed, preferably with potable water, toremove loose debris and to pre-wet any dried drilling mud for ease ofremoval by the cleaning tool 24. Next, the motor mount 28 is installedby sliding the guide bars into the auxiliary tubes. With the guide barsfully inserted, the position of the air motor can be adjusted to centerthe axis of rotation of the motor output shaft to account for variationsin the positioning of the auxiliary pipes. The mounting assembly is thenpulled back out (about 3.5 feet), and the first section of drive tube 38is installed on the motor drive. This provides sufficient clearance forthe cleaning tool 24 on the end of the first section of drive tube 38.The cleaning tool is then placed inside the end of the main pipe 10.Next, the air line 36 is connected to the motor and the air regulator 48is adjusted to zero. The air pressure is then slowly increased until thecleaning tool 24 just starts to turn. Note that due to the coefficientof friction, more air pressure will be required to start turning thetool than is required to keep the tool turning.

The cleaning tool can then be manually run into the pipe for cleaningthe first portion. Alternatively, the wire line 18 can be pushed throughthe pipe 10 and connected to the swivel 22 prior to making up the toolto the air motor. With this setup, the winch motor is used to pull thecleaning tool through the pipe. When the motor mount 28 contacts the endof the pipe, the air supply 36 is shut off, and the mount 28 is pulledback to provide enough clearance to attached another 3′ section of drivetube 38. The procedure is repeated until the entire length of the pipe10 has been cleaned with the cleaning tool. The process is completed byflushing the pipe with water until the water at the other end of thepipe is clear of debris.

Another setup is required for cleaning the smaller auxiliary pipes. FIG.2 depicts the arrangement for cleaning such smaller diameter 3 and 4inch nominal ID pipes, which may otherwise be referred to herein astubulars or lines. These are, for example, a choke and kill line 50 anda mud booster line 52, respectively. A similar arrangement is used forcleaning both lines, and the cleaning tool comprises a cutting orgrinding tool 54 which is used primarily to remove welds which extenddown into the lines 50 and 52. Removing the protruding welds ensuresthat the inspection tools which are later to be used have room to travelfreely through the pipes.

Immediately behind the cutting tool 54 is a wire brush 56 for removingrust and loose debris from the inside of the pipe. Immediately behindthe wire brush 56 is a centralizing sleeve 58, preferably made of a hardplastic or other appropriate material, to align the cutting tool 54 andthe wire brush 56. The cutting tool, wire brush, and centralizing sleeveare all coaxially mounted to a drive shaft 60 which is coupled to an airmotor 62 for high speed rotation of the coaxially mounted tools. The airmotor 62 is provided with pressurized air from a rig air supply line 64which is provided with a valve 66 which provides both positive shutoffand speed control by controlling air pressure to the air motor 62. On acommon line with the rig air supply line 64 is a water supply line 68which provides water under pressure to water jet nozzle 70 which washesrust, dust, and other debris forward through the pipe.

Visual Inspection

FIGS. 3 a and 3 b depict a structure for visual inspection of theinterior surface of the main pipe 10. An alternative means for visualinspection uses a camera mounted on a TOM tool, described below.

The structure of FIG. 3 a includes a camera carrier 72 on which ismounted a camera 74 having a wide angle lens for completecircumferential viewing of the interior of the pipe. The carrier 72 isretained securely centered within the pipe 10 with a plurality of springloaded wheels 76. The carrier with camera mounted thereon is drawnthrough the pipe with a harness 78 coupled to the carrier with swivelmounts 80. The harness 78 is joined to the wire line 18 wound onto thewinch 20 spool, as previously described.

The camera 74 provides a signal over a signal line 82 to a televisionand video cassette recorder 84 and a computer 86 to provide real timeviewing of the camera view and to provide a record of the visualinspection. The signal line 82 is preferably taken up on a take-up reel88 to keep the slack out of the signal line 82 during the inspection. Asthe wire line 18 is taken up by the winch, it passes through a digitallinear placement transducer or encoder 90, which is simply an idler ofprecisely known diameter so that the position of the carrier 72 alongthe longitudinal direction of the tubular is known. The encoder 90 iscoupled to the computer 86 by a signal line 92. The encoder mayalternatively be mounted to the carrier 72, and the signal line 92 maythen be included with the signal line 82.

Because of constricted space, a different structure is called for whenviewing the interior surface of the smaller lines 34, as depicted inFIGS. 4 a and 4 b. A similar arrangement is provided for the inspectionof both 3″ and 4″ lines. The system of FIGS. 4 a and 4 b uses the samemounting for the winch as previously described, but now it can be seenthat the winch is rotatable on its mount so that the wire line 18 may bedirected onto a line 34.

The camera 74 is mounted to a centralizer sleeve 94, which is coupled tothe wire line 18 with a swivel mount 96. The centralizer sleeve adaptsthe same camera to different ID auxiliary lines. The signal from thecamera 74 is provided over the signal line 82 to the television andrecorder 84 and to the computer 86 as previously described. The camerais drawn through the auxiliary line 34 by the wire line, which passesover the encoder 90 so that the longitudinal position of the camera isknown at all times. The wire line passes over an idler pulley 98 whichpresses against the encoder 90.

The purpose of the visual inspection of the interior surface is to showup any obvious surface cracks or corrosion, and to provide for a morecomprehensive ultrasonic inspection to follow. It provides the user witha visual inspection record, through the recorder 84, of the assembleddrilling riser joint internal pipe surfaces, for example, although thesystem and method of this invention may be applicable to other tubulars.

To use the visual inspection system, the camera is installed to theappropriate size adapter sleeve for the line to be inspected, and thecamera cable is fished through the line, starting from the box end tothe pin end, for example. The cable is then connected to the camera, andthe winch assembly is mounted to the end of the riser pipe. The wireline is coupled to the encoder, and the remaining cable connections aremade to the computer and television with recorder. The encoder iszeroed, and the image is viewed on the screen of the television toensure adequate picture quality. Then, using the winch, the wire line isdrawn through the tubular. The user can watch the television whilemaking an inspection record. The procedure should then be repeated forall tubulars to be inspected.

Corrosion Mapping

FIGS. 5 a, 5 b, and 5 c depict the structure for corrosion mapping ofthe interior of the main pipe 10. FIG. 5 a is a side view of a corrosionmapping tool 100, constructed in accordance with the invention,positioned within the main pipe 10. FIG. 5 b is an end view showing themounting hardware for moving the tool 100, and FIG. 5 c is a detail viewof the corrosion mapping tool 100 itself.

Referring first to FIG. 5 c and the corrosion mapping tool 100, the toolcomprises primarily a truncated cylinder 102 with flanges 104 and 106 atthe left and right ends of the cylinder 102, respectively. The cylinder102 is axially oriented along an axis 103, which when in use is coaxialwith the axis of the pipe 10. Mounted to the flange 104 in abuttingcontact is a seal plate 108 which is retained by an end plate 110, heldto the flange with a set of bolts 112, for example. One such bolt 112may be replaced by a lifting eye 114 to assist in transporting the tool100, since the tool 100 is roughly 20″ in diameter and quite heavy. Atthe other end of the cylinder 102, mounted to the flange 106, is an endplate 116, a seal plate 118, and a backing support ring 120, all held tothe flange 106 with a set of bolts 112, for example.

Note that the mounting hardware for the seal plates 108 and 118 is notthe same for each seal plate. The end plate 110 is to the left of theseal plate 108, i.e. away from the flange 104, and the end plate 116 isto the left of the seal plate 118, i.e. in abutting contact with theflange 106. This arrangement provides support for the compliant sealplates when the bend under friction against in the inside diameter ofthe pipe 110 when the tool 100 is drawn through the pipe.

The end plate 116 also provides a mount for a hub 122 held to the endplate 116 with a plurality of bolts 124, for example. The hub receives acoupling 126, which receives a water hose connection 128 (see FIG. 5 a).Water from the water hose connection 128 provides a couplant for thepulse echo signal used in the corrosion mapping as described below. Thehub 122 also includes a water channel 130 leading the flow of water to aflexible tube 132 which carries the water to a penetration 134 throughthe cylinder 102. Thus, the water floods an annular chamber 135 (SeeFIG. 5 a) formed by the cylinder 102, the seal plates 108 and 118, andthe interior diameter of the main pipe 10.

The end plate 110 provides a mount for a cable connector 136 whichreceives a transducer signal cable 138 (See also FIG. 5 a) to bedescribed below. The transducer signal cable 138 terminates in a pulseecho transducer 140, which is mounted in an insert 142 which in turn isinstalled in the cylinder 102. It should be understood that althoughonly one transducer is shown, a plurality of transducers are used inorder to provide a full 360° coverage to map the entire pipe. Thetransducer 140 provides a pulse echo signal to determine wall thicknessof the cylinder 102 in a manner well known in the art. The cylinder 102may also provided with a nipple 144 to receive a lifting ring, ifdesired.

FIGS. 5 a and 5 b show the arrangement for the use of the tool 100. Aspreviously described with regard to the cleaning of the pipe 10, thewinch assembly 12 is mounted at one end of the pipe 10 and the winchassembly is mounted to the flange 16. The winch is driven by a winchmotor 14 and includes a winch spool 20 upon which is wound a wire line18, enough wire line to reach the entire length of the pipe 10. The endof the wire line 18 terminates in a harness 146, which couples to thetool 100 with a set of swivels 148.

The transducer 140 provides a signal over the signal line 138 (which maybe the same signal line 82 as previously described) to the computer 86to provide a record of the corrosion mapping inspection. The signal line82 is preferably taken up on the take-up reel 88 to keep the slack outof the signal line 82 during the inspection. As the wire line 18 istaken up by the winch, it passes through the encoder 90 as before. Theencoder provides position of the tool 100 along the longitudinaldirection of the main pipe 10. The encoder 90 is coupled to the computer86 by the signal line 92. The encoder may alternatively be mounted tothe carrier 100, and the signal line 92 may then be included with thesignal line 82.

To use the tool 100, the wire line 18 and the signal line 138 are fedthrough the length of the pipe 10. The winch assembly 12 is then mountedto the flange 16 and the tool is hooked up to the signal line 138 andthe connecting hose 128. The tool 100 is placed flush with the end ofthe pipe 10, and the encoder is zeroed. Water is then applied throughthe hose connection 128, filling the annular chamber 135. The winchmotor is then turned on, pulling the tool 100 the entire length of thepipe 10 and the position of the tool 100 is known at all times from theencoder. The transducer provides a measurement of wall thickness of theentire pipe 10, which is recorder by the computer 86 for later reviewand analysis.

A similar arrangement is used for the corrosion mapping of the smallertubulars, as shown in FIGS. 6 a, 6 b, 6 c, and 6 d. Referring first toFIGS. 6 c and 6 d, and preferred tool for corrosion mapping of the 3″and 4″ tubulars are shown. A tool 150 is adapted for use in 4″ nominalID tubulars, and a tool 152 is adapted for use in 3″ nominal IDtubulars. The tools contain the same components, which are numbers thesame in FIGS. 6 c and 6 c. Thus, the following detailed descriptionapplied to both tools.

The tool (either 150 or 152) comprises primarily a cylindrical body 154,a left end cap 156, and a right end cap 158. A seal retaining ring 160is mounted to the left end cap 156 with a set of bolts 162, for example,and a seal retaining ring 164 is mounted to the right end cap 158 with aset of bolts 166 for example. The seal retaining ring 160 holds a sealplate 168 in place, and similarly the seal retaining ring 164 holds aseal plate 170 in place. The seal retaining rings 160 and 164 arepreferably secured to their respective retaining rings by a set of bolts172.

The right end cap 158 provides a mount for a nipple 174 and a hoseconnector 176, providing a connection for the water source or hoseconnection 128. When pressurized, water flows through the nipple 174into a set of flow channels 178 to flood the chamber formed by the sealrings, the cylindrical body, and the wall of the tubular. This providesa signal couplant for the pulse echo for the corrosion mapping tool.

The left end cap 156 provides a mount for a two ring 180 to provide ameans for pulling the tool through the tubular. The left end cap 156includes penetrations 182 through which pass signal cables 184 to carrythe ultrasonic test signal from the tool. The signal cables 184terminate at transducers 186, which are mounted in penetrations throughthe cylindrical body 154. It should be understood that enoughtransducers are provided for a complete 360° coverage around thecircumference of the tubular.

FIGS. 6 a and 6 b illustrate the use of the tool. The system of FIG. 6 auses the same mounting for the winch as previously described, and thewinch is rotatable on its mount so that the wire line 18 may be directedonto the tubular 34. The tool 100 is drawn through the tubular 34 by thewire line, which passes over the encoder 90 so that the longitudinalposition of the tool 100 is known at all times. The wire line passesover an idler pulley 98 which presses against the encoder 90.

To use the corrosion mapping tool 100, the wire line 18 and the signalcable 138 are fed down through the tubular 34 to the end, where the tool100 is attached. The tool is then coupled to the wire line and signalcable, and the hose connection 128 is attached. The tool is registeredwith the end of the tubular, and the encoder is zeroed. With waterpressure supplied by the hose connection 128 to provide a couplant forthe transducers, the tool is drawn all the way through the tubular,measuring wall thickness and providing measurements to the computer.

Time of Flight Diffraction Inspection

The tool for performing Time of Flight Diffraction (TOFD) is notdescribed in detail, because the tool may be acquired from ScanTech,1212 Alpine Suite A, Longview Tex. 75606. Further, the TOM technologyitself was adapted from techniques provided by AEA Technology plc, whoseregistered office is at 329 Harwell, Didcot, Oxfordshire OX11 ORA,United Kingdom. The technique will be described in sufficient detail fora complete understanding of the present invention.

In summary, the TOM scanner system includes a very maneuverable crawlerunit with four, large diameter rare earth magnetic wheels. The magneticwheels grip the interior surface of the pipe 10 so that the crawler canbe guided the entire length of the pipe. The crawler is remotely steeredby the user, and the wheels include surface conforming suspension. Thecrawler is motor driven, and the motor is preferably a water shielded,hightorque, rare earth electric motor. All wiring, including controlsignals and inspection signal cables are shielded. The encoder,previously described, is preferably enclosed within the crawler forprecise position measurement and indication. The TOM transducers aredoublegimbaled for a fill range of motion.

FIG. 7 shows a crawler 200 carrying the TOM system in operation. Twosuch crawlers 200 are shown in FIG. 7, in order to show inspection of alongitudinal weld 202 and a girth weld 204, while the system preferablyincludes a single crawler. The crawler preferably includes a singleumbilical 206, which includes a bi-directional signal cable 208 and awater supply line 210. As previously described, the water supply line210 provides the water couplant for the TOM transducers. The signalcable 208 is preferably taken up on the take-up reel 88 to keep theslack out of the signal cable 208 during the inspection.

The signal cable includes a number of lines, including a video signalline 212 from the on-board camera to the television and video cassetterecorder 84 and the computer 86 to provide real time viewing of thecamera view and to provide a record of the inspection. The signal cable208 further includes a signal line 214 from the encoder for preciseposition measurement and indication, a signal line 216 for carrying theTOM signal to the computer, and a maneuvering control signal line 218from a remote, joystick control 220.

In operation, the crawler 200 is driven down the pipe, and the operatorviews the interior of the pipe at the television monitor 84, controllingthe movement of the crawler with the joystick control 220. When a girthweld 204 is encountered, the crawler is turned and driven around thecircumference of the pipe.

FIG. 8 a depicts the arrangement for the performance of TOM testing insmaller tubulars in accordance with this invention. FIGS. 8 b and 8 cdepict the tools of the invention for conducting TOFD testing in 4″ and3″ nominal ID tubulars, respectively. The tools are identical, with theexception of an adapter sleeve 230 to adapt the tool to the larger 4″ IDtubular. Thus, the following description will apply to both FIGS. 8 band 8 c.

A TOM tool 232 comprises a body 234, a left end cover 236, and a rightend cover 238. Within the body is a carrier and slide assembly 240,which provides a cam action for a set of yokes 242. The yokes support aset of shoes 244 in which are mounted the TOM transducers 246. The shoes244 are shown in FIGS. 8 b and 8 b in the deployed position in order forthe shoes to make contact with the interior surface of the small tubularin preparation for the TOM test. The carrier and slide assembly 240 ismoved transversely by air pressure from an air cylinder 248 which issupplied from a nipple 250 and air connection 252. Actuation orretraction of a rod 254 from the air cylinder moves the carrier andslide assembly 240 back and forth, so that the yokes ride up and down onthe slides, deploying and retracting the shoes.

The body also retains a connector 256 for a water connection. The waterfrom the water connection, as previously described, serves as a couplantfor the TOM signal. The body is firmly connected to a drive arm 258which provides a means for rotating the tool 232 in a rotary motion forcomplete circumferential coverage of the TOM test. The drive arm 258 ispreferably connected to a square tube drive means 260 (FIG. 8 a) byremovable screws 262. At the opposite end of the body is a signal cableconnector 264 for connecting the tool to the computer, preferably by wayof a pre-amplifier 266 (FIG. 8 a). At the same end of the body is aneyebolt connection 268 for pulling the tool through the tubular.

FIG. 8 a shows the use of the tool 232 in a small diameter tubular inperforming the TOM test. As previously described with regard to the useof other tools, the wire line 18 is coupled to the eyebolt 268 and thenback to the winch assembly 12 driven by a winch motor 14 and the winchassembly 12 is adapted for mounting to the flange 16. The wire line 18is pulled over an idler pulley 98 which contacts the encoder 90 toprecisely locate the tool 232 within the tubular. The signal cable 264is wound to a takeup reel 88 to keep slack out of the cable. At theother end of the tubular are provided the drive means 260, a watersupply connection 270 for the water couplant, and an air supplyconnection 272 for coupling to the connection 252 (FIGS. 8 b and 8 c).

To use the tool 232, the signal line 264 and the wire line 18 are fedthrough the tubular and connected to the tool. The air and waterconnections are made up, and rotating drive means 260 is connected.Then, the tool is registered with the end of the tubular, and theencoder is zeroed. The tool is the pulled through the tubular androtated by the rotating drive means 260, imaging the tubular forinternal flaws. The computer captures the image for later review andanalysis.

The principles, preferred embodiment, and mode of operation of thepresent invention have been described in the foregoing specification.This invention is not to be construed as limited to the particular formsdisclosed, since these are regarded as illustrative rather thanrestrictive. Moreover, variations and changes may be made by thoseskilled in the art without departing from the spirit of the invention.

1. A system for inspecting a tubular comprising: a) a corrosion mappingtool, the corrosion mapping tool comprising: i) a substantiallycylindrical body defining mutually opposed ends; ii) a flange on each ofthe ends of the body; iii) a substantially circular seal plate on eachflange; iv) a pulse echo transducer on the body; v) an end plate on thebody; and vi) a hub on the end plate, the hub including a couplingadapted to receive a water hose connection; vii) a water channel in thehub terminating at the coupling; xiii) a flexible tube in fluidcommunication with the water channel; and ix) a penetration through thebody, wherein the flexible tube is in fluid communication with thepenetration, and wherein the water channel, the flexible tube, and thepenetration are adapted to carry water to flood an annular chamberdefined by the body, the seal plates, and the interior surface of thetubular; and b) a drawing system removably coupled to the inspectiontool with a wire line, the drawing system adapted to pull the inspectiontool through the tubular.
 2. The system of claim 1, further comprisingan encoder to locate the position of the inspection tool within thetubular.
 3. The system of claim 2, wherein, in use, the wire line passesover the encoder, the encoder providing an indication of the position ofthe inspection tool within the tubular as the wire line passes over it.4. The system of claim 1, further comprising: a) a cable connector onone of the flanges to receive a signal from the transducer; and b) asignal cable to connect the cable connector to a computer exterior thetubular.
 5. The system of claim 1, wherein the pulse echo transducercomprises a plurality of transducer elements and wherein the pluralityof transducer elements are arranged circumferentially around the body.6. The system of claim 5, wherein the transducer elements provide a 360°coverage of the inside of the tubular.